You might be happier with the mobile charger in the car. I've gone on a few trips and forgotten mine at home, denying myself the ability to charge on a 14-50.
If things hold up the way they are now, you might be able to sell the HPWC on eBay for close to what you paid for it.
I usually take the mobile charger with me on trips. But, luckily Superchargers have been plentiful where I have gone.
The Signature HPWC will cost $0, except for the install costs.